Papal conclaves are notoriously hard to predict, but oftentimes factions are broken along regional lines. The concerns of Cardinals from the developing world are quite different from those of Europe or the Americas, and historically Cardinals vote for the new pope based on such concerns, a study from Adam Brickley found.

So from the most basic level of analysis, it's important to know what the electoral base is made up of. Here's the regional breakdown of Cardinals eligible to vote:

Walter Hickey/BI

You'll notice that the Cardinals are overwhelmingly European — more than half hail from Catholicism's home region — and the Europeans are overwhelmingly Italian.

A pope needs a two-thirds plus one majority — 78 votes in this case — to win. A Cardinal who sweeps the rest of the world will still need 23 Europeans to back him, making the Old World bloc a crucial one.

This isn't to say that the pope is guaranteed to be from Europe, just that most of the people who elect him probably will be.